A preliminary model for 3-D rheological structure of the lithosphere in North China

Abstract3-D structures of velocity and temperature are obtained using the data of P-wave velocity and heat flow in North China (105°E—124°E, 30°N—42°N). Taking into account the effect of three main rheological mechanisms, namely friction sliding, brittle fracture and creep in the lithosphere, the 3-D structures of the rheological strength and viscosity in the lithosphere in North China are calculated. The results show that the strength and viscosity in the lithosphere have layering characteristics. Under the strain rate of 10−15 s−1, the upper part of the upper crust is in the brittle region and the lower part of the upper crust may be in the ductile region dominated by creep; the middle crust can be in the brittle region dominated by brittle fracture, or the upper layer of brittle fracture and lower layer of creep ductile; the lower crust almost is in the creep region dominated by creep. In addition, the strength varies horizontally, which has a close relationship with geotectonics. The influence of velocity structure and temperature structure on the rheological structure is discussed and some suggestions to improve the study of lithospheric rheological structure are put forward.